III. Feature Description

A. Forged Stainless Steel Construction: Strength & Hygiene

• Defect-Free Structure: Forging compacts the stainless steel grain, eliminating porosity, shrinkage, and internal cracks common in cast valves. These defects can trap media, bacteria, or cleaning agents—posing contamination risks. In a dairy processing plant, forged valves maintained hygiene compliance for 5+ years, while cast alternatives required replacement after 18 months due to bacterial growth in porous areas.
• Corrosion Resistance: 304/316L forged stainless steel resists corrosion from acidic media (e.g., tomato sauce, vinegar) and sanitizing agents (e.g., sodium hypochlorite). 316L’s molybdenum content enhances resistance to chlorides—critical for coastal facilities or processes using salt-based cleaners.
• Smooth Surface Finish: Forged components are easier to precision-polish to Ra ≤0.8μm than cast parts, as they lack surface irregularities. This smoothness prevents media adhesion and ensures CIP/SIP processes remove all residues.

B. Hygienic Design Principles: Contamination Prevention

• No Dead Legs or Crevices: The valve’s internal geometry eliminates dead legs (unflushed areas where media can stagnate) and crevices (between components where bacteria grow). The body cavity is streamlined, with a full-port ball that, when open, creates a continuous flow path—ensuring cleaning fluids reach every wetted surface.
• One-Piece Ball: A single-piece forged ball (no welds or seams) eliminates potential contamination points. Welded balls, by contrast, can have micro-gaps where bacteria colonize—even after polishing.
• Smooth External Surfaces: The valve’s exterior is polished to Ra ≤1.6μm, resisting dirt, water, and cleaning agent buildup. This facilitates daily washdowns (common in food/pharmaceutical plants) and prevents cross-contamination from external debris.

C. Manual Operation: Simplicity & Reliability

• No External Power Dependencies: Unlike pneumatic or electric valves, manual operation requires no air lines, electrical connections, or control systems—reducing complexity and failure points. This is ideal for small-scale facilities or remote areas where power/air is limited.
• Ergonomic & Lockable Handwheel: The grooved, non-slip handwheel is easy to grip with gloved hands (standard in hygiene protocols). The lockable feature prevents accidental or unauthorized operation—critical for GMP-compliant processes where valve position directly impacts product safety.
• Low Maintenance: Manual valves have fewer moving parts (no actuators, solenoids, or sensors) than automated alternatives, reducing maintenance requirements. Routine upkeep is limited to packing replacement (every 2–3 years) and surface cleaning—minimizing downtime.

D. Food-Grade PTFE Sealing: Leak-Tight & Non-Reactive

• Non-Toxic & Non-Reactive: PTFE is inert, meaning it does not react with food, pharmaceutical, or cosmetic media—preserving product taste, purity, and efficacy. It is FDA-approved for direct food contact and does not leach harmful substances.
• Bubble-Tight Sealing: Class VI leakage ensures no media escapes, preventing product loss and cross-contamination. In sterile pharmaceutical processes, this eliminates the risk of airborne contamination from leaking valves.
• Wear Resistance: PTFE’s low-friction properties reduce wear on the polished ball surface, extending valve life. Even after 50,000+ open/close cycles, the seat maintains sealing integrity—outperforming rubber seals in high-cycle applications (e.g., beverage filling lines).

IV. Manufacturing Process & Quality Control

A. Raw Material Procurement & Inspection

• Stainless Steel Verification: Forged 304/316L blanks undergo spectral analysis (XRF) to confirm chemical composition (Cr, Ni, Mo content) and compliance with ASTM A182. Mechanical testing (tensile, yield, impact) verifies strength properties (≥485MPa tensile).
• Non-Destructive Testing (NDT): Forged components (body, bonnet, ball) undergo ultrasonic testing (UT) to detect internal defects (cracks, inclusions) and magnetic particle testing (MPI) to inspect surface flaws—only defect-free components proceed to machining.
• PTFE Seat Validation: Food-grade PTFE resin is tested for purity (≥99.5% PTFE), tensile strength (≥20MPa), and compliance with FDA 21 CFR 177.1550. Resin batches failing any test are rejected to prevent contamination risks.

B. Forging Process

• Billet Heating: Stainless steel billets (304/316L) are heated in a controlled-atmosphere furnace to 1100–1250℃—a temperature range that maximizes plasticity while avoiding grain growth.
• Precision Forging: Heated billets are forged into body, bonnet, and ball shapes using hydraulic presses (500–1000 tons) and custom dies. Forging ratio is maintained at ≥3:1 to ensure dense grain structure and uniform mechanical properties.
• Solution Annealing: Forged components undergo solution annealing (304: 1010–1120℃; 316L: 1040–1150℃) to relieve forging stresses, restore corrosion resistance, and improve machinability. Components are water-cooled to prevent carbide precipitation (which reduces corrosion resistance).
• Shot Blasting: Forged parts are shot-blasted to remove surface scale and oxide layers—preparing them for precision machining.

C. Precision Machining

• CNC Turning & Milling: Body, bonnet, and ball are machined on 5-axis CNC equipment to ASME B16.34 tolerances. Key machining steps:
  • Body Cavity: Honed to a smooth finish (Ra ≤0.8μm) and streamlined to eliminate dead legs.
  • Ball: Precision-ground to spherical accuracy (≤0.005mm) and polished to Ra ≤0.6μm. The ball’s sealing surface is lapped to match the PTFE seat for tight sealing.
  • Flange Faces: Machined to ASME B16.5 flatness (≤0.02mm/m) and polished to Ra ≤1.6μm for gasket seating.
  • Stem: Turned and ground to precise diameter (±0.01mm) and polished to Ra ≤0.4μm to minimize packing friction.
• Dimensional Inspection: All machined components are inspected with coordinate measuring machines (CMMs) to verify compliance with design specifications. Surface finish is measured with a profilometer to ensure Ra ≤0.8μm (internal) and ≤1.6μm (external).

D. Polishing & Hygiene Treatment

• Internal Wetted Surfaces: Components are polished using a multi-step process: rough grinding (to remove machining marks), fine grinding (to refine surface), and final polishing (to achieve Ra ≤0.8μm). Polishing is done with food-grade abrasives to prevent contamination.
• Passivation: Stainless steel components undergo passivation (nitric acid treatment) to form a protective chromium oxide layer—enhancing corrosion resistance and preventing bacterial adhesion. Passivation is followed by thorough rinsing with deionized water to remove acid residues.

E. Assembly & Hygiene Testing

1. Component Cleaning: All parts (body, bonnet, ball, seat, stem) are cleaned in an ultrasonic bath with food-grade detergent, then rinsed with deionized water and dried in a HEPA-filtered oven—ensuring no dirt, oil, or debris remains.
2. Seat Installation: The food-grade PTFE seat is pressed into the body’s seat pocket with controlled force (to ensure uniform contact with the ball).
3. Stem & Ball Assembly: The stem is inserted into the bonnet, and the one-piece ball is keyed to the stem—ensuring secure torque transmission.
4. Packing Installation: Multi-layer food-grade PTFE-impregnated graphite packing is installed around the stem, with controlled compression (10–15%) to balance sealing and operational torque.
5. Body & Bonnet Assembly: The bonnet is bolted to the body using 316L stainless steel bolts, tightened in a crisscross pattern to uniform torque (per ASME B18.2.1)—ensuring no leakage at the body-bonnet joint.

• Hydrostatic Seat Test: 1.1× rated pressure (e.g., 1.76MPa for PN16) applied to the seat (bidirectional) for 15 minutes. Leakage is measured via bubble counting—Class VI compliance requires ≤1 bubble/minute for DN15.
• Hydrostatic Shell Test: 1.5× rated pressure (e.g., 2.4MPa for PN16) applied to the body cavity for 30 minutes—no leakage or deformation permitted.
• CIP/SIP Validation: Sample valves undergo CIP (80℃ alkaline cleaner) and SIP (121℃ steam) cycles to verify cleaning efficacy. Post-test, no media residues or bacteria (E. coli, Salmonella) are detected via swab testing.
• Surface Finish Verification: A profilometer confirms internal surfaces meet Ra ≤0.8μm and external surfaces ≤1.6μm.

F. Final Inspection & Packaging

• Visual Inspection: Check for surface defects (scratches, dents), proper polishing, and correct assembly. Valves with surface scratches (depth >0.05mm) are rejected—scratches can trap bacteria.
• Documentation: Each valve is shipped with a Hygiene Certificate (3A/FDA compliance), Material Test Report (MTR) for stainless steel components, and Test Report (hydrostatic/CIP validation).
• Hygienic Packaging: Valves are wrapped in food-grade polyethylene film and packed in cardboard boxes lined with sterile tissue—preventing contamination during transportation. Flange ends are capped with sterile plastic protectors to keep internal surfaces clean.